This invention relates to the field of object location and tracking systems for asset management systems, and more particularly, this invention relates to object tracking and location systems using a plurality of tag signal readers and differentiation of first-to-arrive signals to locate a tag transmitter coupled with an object to be located.
In commonly assigned U.S. Pat. Nos. 5,920,287; 5,995,046; 6,121,926; and 6,127,976, the disclosures which are hereby incorporated by reference in their entirety, a real time location system is disclosed using a plurality of tagged emission (signal) readers that are disbursed throughout a monitored environment, such as a manufacturing environment. The tag signal readers are operative with a location processor to determine which tag signals transmitted from tag transmitters are first-to-arrive signals. The location processor conducts differentiation of the first-to-arrive signals to locate a tag within the monitored environment.
These location and tracking systems provide asset management that not only addresses the need to locate and track different components in the course of their travel through a manufacturing and assembly sequence, but also addresses the more general problem concerning component and equipment inventory control and allow control concerning the whereabouts of any and all assets of a business, factory, educational, military, or recreational facility. In some systems, status information can be provided to a tag transmitter by means of sensors associated with the tag. Typically, the tag signal readers are placed at known locations throughout the environment having the objects to be located or tracked. The system uses time-of-arrival differentiation of repetitive spread spectrum, short duration pulse xe2x80x9cblinksxe2x80x9d from object-attached tags. The system provides the practical, continuous identification of the location of each and every object within the environment of interest, irrespective of whether the object is stationary or moving.
These systems are especially applicable for indoor environments, but usually cannot be applied in some outdoor environments, such as large construction sites, e.g., a pipeline construction area having multiple construction sites that may change often, where there is a requirement to track high value assets and provide information on their location and status based on their geolocation and real-time telemetry information.
There is, therefore, a need for a system that locates high value assets, such as at large construction sites and adjacent xe2x80x9claid down areas.xe2x80x9d It is also desirable to have a mobile system that benefits mobile construction projects, such as the construction of oil and gas pipelines where the actual construction site moves to a different geographic location on a daily basis. Military applications requiring rapid deployment forces and material support should have a system where the departure and landing operations can be facilitated by real-time tracking of the location of high value assets, including personnel, and where a geolocation is integral to integration with other operational systems. Sporting events and other public events would be advantageously served with such a system that rapidly deploys and uses location capability to support public safety for the management of high value assets available at the site.
The present invention advantageously solves the above-identified problems by providing a system for locating an object and is advantageously used in outdoor environments where there is a requirement to track high value assets and provide information on their location and status based on geolocation and real-time telemetry information. The system is relatively easy to set up and can operate in a mobile environment.
In accordance with the present invention, the system for locating an object includes a plurality of tag signal readers that receive wireless tag signals from a tag transmitter coupled with an object to be located. The tag signals have data indicating the identity of the object to which the tag transmitter is coupled. Each tag signal reader includes a global positioning system receiver associated therewith for determining the location of a tag signal reader. A wireless transmitter transmits a wireless data signal incorporating the wireless tag signal and location information of the tag signal reader.
A location processor receives the wireless data signal from the tag signal readers and determines which tag signals are first-to-arrive signals. The location processor conducts differentiation of the first-to-arrive signals relative to the location of the tag signal readers as determined by the global positioning system receivers to locate a tag transmitter and high value asset as an object coupled therewith.
In another aspect of the present invention, the wireless tag signals comprise pseudo random spread spectrum radio frequency signals. The location processor comprises a matched filter correlator that could include matched filter banks having parallel correlators that correlate a received communication signal with time offset versions of a reference spreading code. The location processor could also include a plurality of processors for distributing the processing capability. At least three tag signals can be used for determining the location of the object to be located.
In yet another aspect of the present invention, each tag signal reader includes a plurality of mutually diverse antennas for detecting wireless tag signals at each tag signal reader. Each tag signal reader is formed as a mobile device having a battery for self-powering the tag signal reader. The wireless data signal transmitted from a tag signal reader could comprise telemetry information regarding power levels of a battery within the tag signal reader. The wireless data signal transmitted from a wireless transmitter could comprise a packet signal that includes a header containing global positioning system information related to the location of the wireless transmitter. The global positioning system receiver at each tag signal reader preferably comprises a differential global positioning system receiver.
A method of the present invention is also disclosed and comprises the steps of generating a wireless tag signal to a plurality of tag signal readers from a tag transmitter coupled with an object to be located. The tag signals have data indicating the identity of the object to which the tag transmitter is coupled. Each tag signal reader includes a global positioning system receiver associated therewith for determining the location of a tag signal reader.
The method further comprises the step of transmitting a wireless data signal and incorporating the wireless tag signal and location of the tag signal reader and receiving within the location processor the wireless data signal from the tag signal reader. The method also comprises the step of determining which signals are first-to-arrive signals and conducting differentiation of the first-to-arrive signals relative to the location of the tag signal readers as determined by the global positioning system receivers to locate a tag transmitter and object coupled therewith.